Field of the Invention
This invention relates to an apparatus, of the kind usually known as an optic, for dispensing a predetermined, measured quantity of liquid from an inverted bottle. Such an apparatus comprises a measuring chamber with an inlet at one end which, in use, is connected to the mouth of the inverted bottle, and an outlet opening at the other end through which the measured quantity of liquid is dispensed. The measuring chamber incorporates a double-headed plunger which in a first position closes the outlet whilst leaving the inlet open so that the measuring chamber fills with liquid from the bottle, and in a second position the plunger closes the inlet and leaves the outlet open so that the measured quantity of liquid drains from the measuring chamber. Normally, the plunger is operated either by a bar which is engaged, and lifted, by a glass into which the liquid is dispensed, or by a lever which is also operated by the glass.
In conventional designs of such apparatus, it is possible for the user to dispense less than the full measured quantity of liquid, by removing the glass, and thereby allowing the plunger to return to its first position, before the measuring chamber is entirely empty, and it is one of the objects of the present invention to reduce or eliminate this possibility.